The present invention relates to a suction valve in a following variable displacement compressor. The compressor has a swash plate accommodated in a crank chamber, where the pressure is controlled so as to rotate the swash plate integrally and inclinably with a drive shaft, and a plurality of pistons, which are accommodated in cylinder bores arranged around the drive shaft and reciprocate in accordance with rotation of the swash plate. The inclination angle of the swash plate is adjusted in response to the pressure in the crank chamber, which is changed by adjusting the amount of gas supplied from a discharge chamber to the crank chamber, and the amount of gas relieved from the crank chamber to the suction chamber. Furthermore, flexible suction valves open and close suction ports, and in suction movements of the pistons, the suction valves are pushed up and draw gas through the suction ports into the cylinder bores.
In a piston type compressor, while the suction valves move from a closed position to close the suction ports to the maximum opening position to open the suction ports, vibrations occur at suction valves and this causes suction pulsations. The suction pulsations cause the evaporator in the outer refrigerant circuit to vibrate and generate noise.
In a variable displacement compressor having pistons, the pistons reciprocate with a stroke in accordance with the inclination angle of the inclinable swash plate, and the discharge capacity decreases when the inclination angle of the swash plate decreases. In a small discharge capacity state, an average amount of gas passing through the suction port is small, and the suction valve can hardly contact a stopper for regulating the maximum opening degree due to its small opening degree. As a result, in the variable displacement compressor the vibrations of the suction valve easily occur.
The object of the present invention is to offer an effective suction valve enough to prevent noise or clatter caused by vibrations of suction valves in a variable displacement compressor.
To achieve the above object, the inventors propose a following variable displacement compressor. The compressor has a swash plate accommodated in a crank chamber, where the pressure is controlled, so as to rotate the swash plate integrally and inclinably with a drive shaft, and a plurality of pistons, which are accommodated in cylinder bores arranged around the drive shaft and reciprocate in accordance with rotation of the swash plate. The inclination angle of the swash plate is adjusted in response to the pressure of the crank chamber, which is changed by adjusting the amount of gas supplied from a discharge chamber to the crank chamber, and the amount of gas relieved from the crank chamber to the suction chamber. Furthermore, flexible suction valves open and close suction ports, and in suction movements of pistons the suction valves are pushed up and draw gas through the suction ports into the cylinder bores.
Furthermore, in the present invention, a twisting flexibility regulating means to bend and twist the suction valve, and a maximum opening degree regulating means having a receiving portion receiving the suction valve and regulating maximum opening degree of the suction valve in contact with the suction valve comprise the structure of the suction valve. The maximum opening degree regulating means is formed at the associated cylinder bore as follows. A first distance (between the suction valve at the more twisted side in closed position and a confronting point on the receiving portion) is longer than a second distance (between the suction valve at the other side in closed position and a confronting point on the receiving portion).
Therefore, the suction valve bends while twisting and the opposite side to the twisted side contacts the receiving portion first. Then, as the opening degree of the suction valve becomes larger, the suction valve becomes more twisted. And the twisted side of the suction valve approaches the receiving portion.
Furthermore, in the present invention, the maximum opening degree regulating means is a recess for regulating maximum opening degree recessed in the direction of the reciprocating movement of the piston along the circumferential surface of the cylinder bore. And the receiving portion is a bottom of the recess for regulating maximum opening degree, which is the receiving portion of the recess. Moreover, the receiving portion is inclined in the direction of width of the confronting suction valve.
As for the suction valve, the lower bending flexibility side of the suction valve contacts the shallower stopper side of the recess for regulating maximum opening degree first. Then, as the opening degree of the suction valve becomes larger, the suction valve becomes more twisted. And the higher bending flexibility side of the suction valve approaches the deeper stopper side of the recess for regulating maximum degree of opening.
Furthermore, in the present invention the twisting flexibility regulating means comprises two bending flexibility regulating means of which bending flexibilities are different each other and arranged in the direction of width of the suction valve, so that the distance between the higher bending flexibility side of the suction valve and the confronting receiving portion is longer than that between the lower bending flexibility side and the confronting receiving portion.
As for the suction valve, the lower bending flexibility side of the suction valve contacts the receiving portion first. Then, as the opening degree of the suction valve becomes larger, the suction valve becomes more twisted. And the higher bending flexibility side of the suction valve approaches the receiving portion. Thus, in the arrangement that the bending flexibilities are different each other in the direction of width of the suction valve, the suction valve twists easily when the opening degree of the suction valve becomes large.
Furthermore, in the present invention, the suction valve has a pair of flexible portions separated in width and a closing portion closing the suction port placed adjoining to a pair of the flexible portions. The bending flexibility regulating means is a pair of the flexible portions. And each flexible portion urges the suction valve so as to close the suction port. And the bending flexibilities of a pair of the flexible portions are different.
In the above arrangement, the suction valve twists easily when the opening degree of the suction valve becomes large.
Furthermore, in the present invention, while the thickness of a pair of the flexible portions are equal, the bending flexibilities of them are different, since the width of a pair of the flexible portions are different.
The shorter the width of the flexible portion is, the higher the bending flexibility becomes.
Furthermore, in the present invention, the suction valve has a single flexible portion, and the closing portion closing the suction port placed adjoining to the flexible portion. Moreover, the flexible portion urges the suction valve so as to close the suction port. And the flexible portion, which is biased in the direction of width from the central line of the suction valve, is the twisting flexibility regulating means.
Therefore, the twisting flexibility becomes extremely high.
Furthermore, in the present invention, a part of the closing portion substantially constantly contacts the receiving portion of the recess for regulating maximum opening degree.
Therefore, the vibrations of the suction valve are securely prevented.
Furthermore, in the present invention, a plurality of the pistons are arranged around the drive shaft. The pistons reciprocate in the cylinder bore in accordance with the rotation of the drive shaft. The suction ports are formed in a valve plate defining a suction chamber, a discharge chamber and the cylinder bores. The discharge chamber is formed so as to surround the suction chamber. The gas in the suction chamber is sucked through the suction ports into the cylinder bores. The gas in the cylinder bores is discharged through the discharge ports formed in the valve plate into the discharge chamber.
In the arrangement that the discharge chamber surrounds the suction chamber, a cylindrical suction chamber can be formed. In the arrangement that the suction chamber surrounds the discharge chamber, a circular suction chamber is formed. The cylindrical suction chamber is superior to the circular suction chamber to suppress the suction pulsations.